Sentence Examples with the word open-hearth process

September 23, 2017All Dictionary

The general plan of the open-hearth process was certainly conceived by Josiah Marshall Heath in 1845, if not indeed by Reaumur in 1722, but for lack of a furnace in which a high enough temperature could be generated it could not be carried out until the development of the Siemens regenerative gas furnace about 1860.

Compared with the Bessemer process, which converts a charge of even as much as 20 tons of pig iron into steel in a few minutes, and the open-hearth process which easily treats charges of 75 tons, the crucible process is, of course, a most expensive one, with its little 80-lb charges, melted with great consumption of fuel because the heat is kept away from the metal by the walls of the crucible, themselves excellent heat insulators.

It is in large part because of this shallowness, which contrasts so strongly with the height and roominess of the Bessemer converter, that the process lasts hours where the Bessemer process lasts minutes, though there is the further difference that in the open-hearth process the transfer of heat from flame to charge through the intervening layer of slag is necessarily slow, whereas in the Bessemer process the heat, generated as it is in and by the metallic bath itself, raises the temperature very rapidly.

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To enlarge the scale of operations makes strongly for economy in the open-hearth process as in other high temperature ones.